DESCRIPTION(provided by applicant): This revised competing renewal application requests continuation of the Iowa Cochlear Implant Clinical Research Center. We have been engaged in clinical outcomes research studying cochlear implant application in children and adults. Speech perception with cochlear implants has improved to the point where selection criteria for implant consideration is poorly defined. Refining the criteria for cochlear implantation is one of the more important issues facing clinicians. The overall goals of the proposed research are to 1) study expansion of selection criteria for implantation to include adults with more hearing and earlier implantation in children, 2) develop a reliable evaluation strategy including accurate assessment of auditory thresholds to determine if a child is a candidate for a cochlear implant by 12 months of age, 3) develop and evaluate novel signal processing for speech perception and music appreciation, 4) evaluate the combination of electrical signal processing and acoustical amplification in adults with more residual hearing using a newly designed short electrode implant, 5) refine and expand the use of electrophysiologic measures to improve fitting of existing and high rate speech processors for young children and adults, 6) assess the communication outcomes (speech production, language, reading, writing, and music appreciation) of children with hearing impairment using hearing aids and those with implants to determine if implant selection criteria should be expanded to include children with more hearing, 7) study the benefits of binaural cochlear implants, 8) determine the factors that affect the long-term benefit of cochlear implants in children and adults. The proposed application will test multiple hypotheses by studying 257 previously implanted adults and children, 120 newly recruited postlingually deafened adults and prelingually deafened children, and 20 adults with more residual low frequency hearing. The 120 adults and children will receive new high rate signal processing implants that include telemetry to measure the cochlear EAP (Nucleus and Clarion). The 20 adults with residual hearing will be implanted with a short electrode implant recently developed by the Iowa implant team. 75 hearing impaired children using hearing aids and 25 normal hearing infants will be recruited for control studies. Four research projects, Patient Care and Technical Support Core B will address the above goals. The 4 research projects are highly integrated and depend on data from each other to answer the experimental questions proposed.